Pregnant women are exposed to endocrine disrupting chemicals such as phthalates and bisphenol A (BPA) through their use of personal care products and plastics. In animal models, phthalates and BPA cause developmental abnormalities, but littie is known about whether these chemicals are associated with adverse developmental outcomes in humans. The proposed pilot study will develop novel methods to assess the impact of prenatal BPA or phthalate exposure on sexually dimorphic physical and behavioral endpoints during the first few months of life and it will identify reliable and valid measures of cognitive function in newborns that are sensitive to prenatal chemical exposure and predictive of lasting cognitive deficits. The overall hypothesis of the proposed pilot study is that maternal exposure to phthalates and/or BPA is associated with adverse developmental outcomes in their offspring. The specific objectives of the proposed project are to: 1) assess exposure to phthalates and BPA in a sample of pregnant women, 2) examine the association between prenatal phthalate and BPA exposure and physical development in infants, 3) examine the association between prenatal phthalate and BPA exposure and cognition in infants, and 4) investigate whether polymorphisms in estrogen receptor (ER) alpha and ER beta increase susceptibility to prenatal phthalate or BPA exposure. To complete the proposed work. 150 pregnant women age 18-40 and their infants will be recruited from a local hospital. The pregnant women will complete a 24-hour product use diary and provide urine samples for assessments of total BPA and 9 phthalate metabolites. In addition, pregnant women will donate cord blood for measurement of selected ER polymorphisms. Key physical and cognitive outcomes will be assessed at birth, and cognitive outcomes will also be assessed at 4.5 and 7.5 months of age. The relationship behween measures of exposure and reported product use, and the relationship behween maternal exposures and physical or cognitive outcomes in infants will be examined in statistical regression models. The proposed study will provide important pilot data about the nature of phthalate and BPA exposure in pregnant women and the risk of developmental abnormalities in their infants. The results will provide a strong basis for expansion of the pilot birth cohort into a larger prospective birth cohort with longitudinal follow-up of the children from birth through puberty.